[javascript] Sort array by firstname (alphabetically) in Javascript

Basically you can sort arrays with method sort, but if you want to sort objects then you have to pass function to sort method of array, so I will give you an example using your array

user = [{
bio: "<null>",
email: "[email protected]",
firstname: 'Anna',
id: 318,
"last_avatar": "<null>",
"last_message": "<null>",
lastname: 'Nickson',
nickname: 'anny'
},
{
bio: "<null>",
email: "[email protected]",
firstname: 'Senad',
id: 318,
"last_avatar": "<null>",
"last_message": "<null>",
lastname: 'Nickson',
nickname: 'anny'
},
{
bio: "<null>",
email: "[email protected]",
firstname: 'Muhamed',
id: 318,
"last_avatar": "<null>",
"last_message": "<null>",
lastname: 'Nickson',
nickname: 'anny'
}];

var ar = user.sort(function(a, b)
{
  var nA = a.firstname.toLowerCase();
  var nB = b.firstname.toLowerCase();

  if(nA < nB)
    return -1;
  else if(nA > nB)
    return 1;
 return 0;
});